(function ($) {
    $.fn.extChange = function (callback) {
        var value = $(this).val();
        setInterval($.proxy(function () {
            if (callback) {
                var newValue = $(this).val();
                if (value != newValue) {
                    value = newValue;
                    callback.call(this, window.event);
                }
            }
        }, this), 300);
    };
})(jQuery);